This circuit can be used to convert
20-30v DC to 5v DC. Due to this circuit we can charge mobile with Laptop charger fastly. If you want to charge your mobile and there is no mobile charger then you can charge your mobile with this circuit.
A voltage regulator is used to produce a constant linear output voltage. It’s generally used with AC to DC power supply. And also it can be used as well as a DC to DC voltage converter. To regulating low voltage, most used device is one single IC. 7805, 7812, 7905 etc. 78xx series are design for positive and 79xx series are for Negative voltage regulator.
The circuit is built around 7815 and 7805 voltage regulator ICs. 7815 is connected to provide voltage regulation with output of + 15 V dc from this unit. An unregulated, input voltage Vin is filtered by capacitor 470uf, and connected to the pin .1 (IN terminal) of IC. The pin 2 (OUT terminal) of the IC provides a regulated + 15 V which is filtered by capacitor 470uf (mostly for any high frequency noise). The third pin (GND terminal) of the IC is connected to ground. While the input voltage may vary over some permissible voltage range, and the output load may vary over some acceptable range, the output voltage remains constant within specified voltage variation limits.
7805 is a three terminal +5v voltage regulator IC from 78XX chips family. They are linear positive voltage regulator IC; used to produce a fixed linear stable output voltage. Its output voltage is +5V DC that we need. You can supply any voltage in input; the output voltage will be always regulated +5V.It is recommended to input voltage less than 18v and more than 8v. There are two capacitors of 1uf used two capacitors in this voltage regulator circuit, they aren’t mandatory to use. But it will be best if you use them. Due to this, 7815 converts 20-30vDC to 15Vdc and 7805 will convert 15vDC to 5vDC.